Tube bending machine



May 3l, 1955 N. E. GRACE Erm. 2,709,473

TUBE BENDING MACHINE I Filed Aug. 18. 1947 3 Sheets-Sheet 1 BY Wal/1 W TTCRNEYS.

N. E. GRACE I'AL TUBE BENDING MACHINE May 31, 1955 5 Sheets-Sheet 2 Filed Aug. 18. 1947 iNVENTORS S Y E N T T A TUBE BENDING MACHINE Filed/Aug. 18. 1947 3 SheetsSheet 3 t. n fil/1A f INVENTORS TUBE BENDING MACHINE Nelson E. Grace and Gilbert J. Ozenne, Torrance, Calif., assignors to Doak Aircraft Co., Inc., Torrance, Calif., a corporation of California Application August 18, 1947, Serial No. 769,280

7 Claims. (Cl. 15S- 40) The present invention relates to a machine arranged to bend elongated elements such as hollow tubing and finds applicability in many fields, including the field of manufacturing chairs of the type in which the bent tubmg serves as a frame member of the chair.

An obiect of the present invention is to provide an improved tube bending machine arranged to successfully bend hollow circular tubing into many different forms and shapes without attening or galling the tubing at the bends.

Another object of the present invention is to provide an improved tube bending machine having as one of its various features a pair of cooperating die members, one of which is rotatably mounted and the other of which is slidably mounted, and arranged so that the velocity of the two die members with respect to the tubing is substantially equal in a bending operation.

Still another object of the present invention is to provide an improved tube bending machine arranged to bend a piece of tubing at more than one place with the angles of bend in such places being automatically controlled.

Yet another object of the present invention is to provide an improved tube bending machine which incorporates tube gripping means associated with a pair of bending die members, the gripping means being automatically effective to grip the tubing before it is bent by motion of either one of the die members.

Yet another object of the present invention is to provide an improved tube bending machine characterized by its simplicity, ease of operation and its capability of bending hollow wall tubing without flattening or galling the tubing.

Yet another object of the present invention is to provide an improved tube bending machine of the hydraulic or pneumatic types whereby successive bends of predetermined angularity may be made in a piece of tubing inserted into the machine.

Yet a further object of the present invention is to lprovide an improved tube bending machine which may be operated by unskilled personnel to bend a piece of tubing in the shape of the framework of conventional present day summer porch chairs, for example, of the type which have a cloth back and a cloth seat.

Yet another object of the present invention is to provide an improved tube bending machine arranged to bend a piece of tubing at a plurality of places in consecutive order with the angularity of bend in each place being of predetermined angularity.

Still a further object of the present invention is to provide an improved tube bending machine incorporating a pair of movable cooperating bending dies which during the bending operation have no resulting relative movement with respect to the tubing at their point of contact with the tubing.

Yet a further object of the present invention is to provide an improved tube bending machine of the hydraulic type in which means are present to initially grip the tubttes Patent ice ing and then to produce movement of at least one bending die member.

Still a further object of the present invention is to provide a tube bending machine allowing the bending of a framework of a summer porch chair in a minimum amount of time with a minimum amount of effort by unskilled personnel.

The features of the present invention which are believed to be novel are set forth with particularity in the appended claims. This invention itself, both as to its organization and manner of operation, together with further objects and advantages thereof, may be best understood by reference to the following description taken in connection with the accompanying drawings in which:

Figure l is a view in plan of a portion of a tube bending machine incorporating the present invention.

Figure 2 is a view in side elevation of the apparatus shown in Figure 1.

Figure 3 is a view taken substantially in the direction indicated by the arrows 3 3 in Figure 2.

Figure 4 is a perspective view showing some of the hydraulically controlled elements of the machine shown in Figure l.

Figure 5 is a sectional view taken substantially on the line 5 5 of Figure l, with a piece of hollow wall tubing in position preparatory to bending.

Figure 6 is a sectional view corresponding to the sectional view shown in Figure 5 but with the corresponding parts in one of the positions they assume during a bending operation.

Figure 7 is a sectional view taken substantially on the line 7 7 of Figure 5.

Figure 8 is a view taken substantially in the direction indicated by the arrows 8 8 of Figure 3.

The machine shown in the drawings includes two pairs of tube bending dies or die members 10, 11 arranged symmetrically about the longitudinally extending axis of the machine so that if desired, either one or two bends may be made simultaneously. Because of the symmetrical disposition of the bending die members 10, 11 and their identical nature, it is necessary to describe and show as in Figure 4, only one pair, it being understood that the constructional features and operation of the other pair is identical.

The die member 10 is in the form of a segment of a circle and has a peripheral arcuate semi-bore die face, the center of which corresponds to the center of rotation of the shaft 12 upon which the die member 10 is mounted, the shaft being rotatably mounted on the frame 15, 16. The other cooperating die member 11 is straight and is slidably mounted in its stationary guide bearing 13 and has a straight semi-bore die face which Cooperates with the aforesaid arcuate die face in member 10 to engage tubing therebetween. Both of these die members 10, 11 are of course, mounted on the stationary frame or framework of the composite machine.

The stationary framework of the machine comprises a pair of parallel spaced channel members 15, 16 which have laterally extending supporting 'plates or channel members 17, 18, 19 and 20 fastened thereto with spaced channel members 21, 22, 23 and 24 extending laterally outwardly from the channel members 15, 16, respectively, upon which they are fastened to, in turn, support the stationary guide bearings 13 for the die members 11.

Mounted for rotation on this stationary framework is the rotatable shaft 12 which is journalled in the spaced bearing members 25, 26 mounted respectively on the channel members 16 and 15 and which has fastened thereto for rotation the centrally located gear Z7 and sprocket wheel 28.

The gear 27 forms one component of the rack and pinion arrangement 30, 27 with the rack 36 mounted for slidi .g movement in its guide bearing 31 which in turn is supported on the spaced stationary plates i8, 19. The mutilated sprocket gear 2S is arranged to turn a chain 32 mounted thereon, one end of the chain 32 being anchored on the sprocket hub 33 and the other end of the chain 32 being attached to a pawl actuating lever element Sii, to, as described more fully later, automatically condition the machine to produce successive bends of predetermined angularity.

The rack member 3i? is attached through the piston rod di? to the double-acting piston 4i disposed in the fluid pressure` cylinder 42 for movement either by fluid entering the cylinder 42. through conduit 43 or conduit 4d. This cylinder 42 may be pivotally connected to the stationary plate 2@ as indicated in Figure l to allow automatically any necessary alignment when and as the piston il is being moved. Thus, when the piston il is moved in response to iluid pressure within the chamber 42, the rack Si) is also moved, and pinion 27 and shaft 12 are rotated to rotate the bending die member 1i). Thus, hydraulic means including piston 4l and cylinder 42 is provided for actuating or moving the die member l@ relative to the die member l1, and such hydraulic means may be connected with iiuid pressure source 7G.

However, before the die member if? is thus rotated in a bending operation, the gripping clement or tube clamping means which serves to clamp tubing to the die member lil, and which is slidably mounted thereon is initially actuated by hydraulic means to a position wherein such tube is clamped between the gripping element d and the die member l@ so that there is no tangential movement of such tube on the outer periphery of the die member lil during the subsequent tube bending operation. She particular hydraulic means whereby the gripping member 4S is actuated to gripping position prior to operation of the aforesaid hydraulic means comprising piston il and cylinder #l2 is described later in connection with the description of Figure 4.

The tube gripping element 45 is slidably mounted on the die member i and is normally maintained in spaced relation therefrom by the tension springs iS6 having one of their ends attached to the gripping element 4E and the other one of their ends attached to a combination stop and guide pin .7 on the die member lil which pin extends through the guide apertures 4S in the gripping element. The range oi movement of the gripping element 4S is determined by the engagement of the pin 47 with the walls oi the cooperating slot i3 as shown in Figure 4.

The die member 1li has a cylindrical opening Si) therein into which the plunger ft of the gripping element eX- tends` Fluid under pressure may be introduced from the iluid pressure source or pump "itl into such cylindrical opening 5d to raise the gripping element in the direction indicated by the arrow 52 in Figure S against the action of the tension springs 46. Thus, when pressure is introduced into cylindrical opening 5d through the connecting conduit 53, the gripping element i5 is raised to grip any tubing between the die member lil and such gripping element l5 as indicated in Figure 6.

Assuming that the clamping element shown in Figure 5 is raised to its clamping position and the shaft 12 rotated upon which the die member 1G is keyed, the right-hand end of the tubing is pressed down against the die member 11 and as the die member lil continues to rotate, the die member i1 is moved in a straight line without substantial relative movement between it and the tubing to a position indicated, for example, in Figure 6.

The guide member il is preferably mounted on roller bearings 6d of the radial type to prevent slippage between the tubing and the surface of the die member l1.

These roller bearings, as shown in Figure 7, are mounted on a shaft 61 which may be secured in the stationary plug 62 which in turn may be mounted stationary With the guide bearing 13. The die member 1i is nori mally maintained in the position shown in Figures 4 and 5 and by the tension springs 63 each having one of their ends attached to the outer surface of the guide.

bearing 13 and the other one of its ends attached to the die member 1l.

At the end of a tube bending operation, these tension Springs 63 return the die member l1 to their normal positions, and in order to ease any resulting shock, a dashpot means 6d is incorporated. This dashpot means 64- may comprise a rod member 65 having one of its ends attached to the bearing guide member 13 and the other one of its ends projecting into a cooperating cylindrical opening 56 of enlarged diameter in the member 1l.

Fluid pressure for operating the tube gripping element $5 and for moving the piston 41 and rack member Sil is supplied from uid pressure source or pump iti through suitable conduit means including a sequence valve 7l which may be operated from a remote position by a manually or foot operable rod '72, the inlet of the pump 7) being in communication with reservoir 755A. Upon the first operation of the rod '72, fluid iiows from the pump 7@ through the conduit 74, through the sequence valve '71, through the pressure regulating valve through the conduit 76, and conduit 5.3 to the inlet openings '77 to thereby raise the gripping element 45 and to clamp any tubing between such element 45 and the die member le. After the pressure in the lines S3 and 76 has bccome stabilized at a high magnitude, i. e., the gripping elements l5 have been moved to their raised position, the pressure regulating or pressure responsive valve opens to allow full pressure to exit in conduit and also on the right-hand side of piston di. in Figure 4 to thereby cause the raclr member 36 to move in the direction indicated by the arrow 31. Thus, this pressure responsive valve is arranged to assure operation of the tubing clamping means prior to operation ci the hydraulic means including piston dl and cylinder i312-, and resulting operation or movement of rack 3G. Such movement of the rack 3i) continues until the valve actuating end S2, of the raclr, is moved into a position to actuate the member 83 of the valve element or means Thus, this valve means 8d constitutes a control means and is actuated by the control element 32 upon rotation of the rotatable die member ill to a predetermined position and, when actuated, valve means S4 serves to disable or render ineffective or control the eiectiveness or" the hydraulic means including piston 4i and cylinder di. Upon actuation ci the valve element t', the tluid in conduits 53 and 76 of high pressure is allowed to flow through the Conduit 85' into the lov.' pressure end of the reservoir whereupon the tube gripping elements 45 are released and the raclt member 3% may be returned to its original position yupon subsequent application ot pressure te the left hand end of the double acting piston This subsequent application of pressure is af: omplishcd by actuating the sequence valve 7i in which case fluid ot high pressure ows from lthe pump 7i) tlu'anigh the conduit 74 through the pressure regulating valve S?, through the conduit 43 to the cylinder 42 to thereby move the rack member 3h to the right. 'Ihereafteig aiter the piston 4l has moved to its extreme right position the pressure Within conduit 43 becomes stabilized at a high value and conduit 43 is placed in communication with conduit 3S to thereby release pressure wi thin the cylinder 42.

It is noted that when the piston il is being driven to the left in Figure 4 the fluid on the ieft thereof is expelled 'through conduit d3, valve i7, valve "7l and conduit 88 to the low pressure end of pump i9 or reservoir 76A. When the Vpiston 4l is being driven to the right in Figure 4, the iluid on the right thereo is expelled through conduit 444 through check valve 89, through valve 7l. and through conduit S3 to the low pressure end of pump 7h. Valve 71 in fact contains two valves which are operated 'in sequence by the rod 7?. so that when conduit 36 is placed in communication with valve 57, conduit 74 is placed in communication with conduit 90; and, when conduit 88 is placed in communication with valve 75, valve 87 is placed in communication with conduit 74. These pressure regulating valves 75, 87 and sequence valve 71 are of present day commercial structure purchasable upon the open market and specific details thereof need not be shown and described inasmuch as they are all familiar to persons skilled in the art.

Thus, the rack member may be moved in either direction, but inysequence, upon actuation of the manual control element 72.

It is noted that the amount of rotation of die member is determined by the spacing between the valve member or control means 83 and rack end or control element S2. This spacing may be controlled by selectively and automatically imposing therebetween one of a plurality of shims 92 of variable thickness. These shims 92 are preferably mounted at equal angular distance from one another near the periphery of a rotatable shim turret member 93 which is rotatably mounted on a shaft 94 extending from the plate member 18 so that'they are movable in predetermined order between the control means 83 and control element 82. This turret member 93 is normally biased into engagement with the valve member 83 by means of the coil compression spring 95 having one of its ends engaging the plate member 18, and the other one of its ends engaging the movable collar 98 mounted on the stationary shaft 94. Suitable detent means 99 of conventional type may be interposed between the collar member 9S.and the turret member 93 to index the turret member 93 in any one of seven selected angular positions corresponding to positions where the dilerent shim members 92 are in position for engagement by the rack end.

The coil compression spring 9S presses the turret mem ber 93 against the valve actuating member 83 with little pressure sufficiently low so as not to actuate the valve member 84 but to maintain the turret member 93 firmly in position.

This turret member 93 has associated therewith means for automatically rotating the same upon operation of the hydraulically `operated means including piston 41 and cylinder 42. For this purpose, i. e., in providing these means, the turret member 93 comprises a ratchet wheel which may be turned 1/7 of a revolution by the cooperating pawl lever member 34 which is pivotally mounted at a point intermediate its ends on the stationary shaft 94 with one of its ends having attached thereto a tension spring 100 and the other one of its ends having attached thereto the spring-biased pawl member 101 and the sprocket chain 32. The spring 100 has its other end attached to the stationary frame member 16 to tend to rotate the pawl lever member 34 in the counterclockwise direction in Figure 3 tending to pull the sprocket chain 32 with it. When the shaft 12 is rotated clockwise in Figures 2 and 4, in the bending operation or during forward movement of rack 30, the slack in the sprocket chain 32 attached thereto is taken up by the spring 100 which causes the pawl lever member 34 to move in the counterclockwise direction in Figure 3. Such counterclockwise motion of the pawl member 34 in Figure 3 does not cause the turret member 93 to be moved, but such turret member 93 is maintained in one of its indexed positions by the detent means 99 illustrated in Figure 8. ln the return movement of rack 30, i. e., in movement of the rack 30 to the right in Figures 2 and 4, immediately after the bending operation, the chain 32 pulls the lever 34 to produce clockwise movement of the same in Figure 3 and resulting engagement of the pawl 101 into driving relationship with one of the notches in the periphery of turret 93 to move the same clockwise in Figure 3 to the neXt indexed position. In other words, upon each return movement of the rack 30 to the right in Figures 2 and 4, the turret 93 is rotated one-seventh of one revolution. It is observed that, since the shim all) members of the same or diterent thicknesses are interposed between the valve member 83 and the rack end 82, the die members 10 are rotated the same or different corresponding angular distances in the tube bending operation to produce bends of corresponding angularity.

The stationary framework may have mounted thereon positionable stop members 105, 106 in the path of movement of a tube inserted into the machine whereby the p osition of the bend from the end of the tube abutting such stops 105, 106 may be accurately determined.

In operation, either one end of tubing or both-elongated ends or legs of bent tubing as the case may be, may be inserted between the pairs of dies 10, 11 with the free ends thereof in engagement with the positionable stop members 105, 106, such elongated ends or legs being suficiently long to permit the bight to clear the parts to the left of the bending dies in Figure 1. When the tubing is thus positioned, the foot operating member 72 is actuated to initially cause the clamping member 45 to raise, to thereby clamp the tubing between the member 45 and the die member 10. Thereafter, the die member 10 begins to rotate pressing the tubing into engagement with cooperating half round die member 11 to move it with the tubing without relative movement therebetween. After the die member 10 has rotated a predetermined distance corresponding to the thickness of a shim member 92 mounted on the indexed turret member 93, the rack end 82 is then in a position to cause the valve member 83 to release the uid pressure which originally caused the tubing to be gripped and the die member to be rotated. After this release of fiuid pressure, the foot operated member 72 is actuated to cause the die member 10 to be rotated in the reverse direction to return it to its normal position. Upon release of pressure the clamp'- ing member 45 and the die member 11 may return to their original normal positions by the action of tension springs 46 and 63 respectively.

In such normal positions, the clamping member 45 is spaced an appreciable distance below the die member 11 to provide a large opening for that purpose as indicated in Figure 5. The removal of the bent tubing is further facilitated due to the use of the arcuate shaped die member which has its lowennost portion spaced immediately above the left hand edge of die 11 in Figure 5. There is thus a suicient clearance between the dies 10 and 11 to allow withdrawal of the bent tubing.

While the particular embodiments of the present invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from this invention in its broader aspects and, therefore, the aim in the appended claims is to cover all such changes and modications as fall within the true spirit and scope of this invention.

We claim: 1. In a bending machine of the character described, a frame, a pair of die members, one of said die members being slidably mounted on said frame and having a straight semi-bore die face, the other one of said die members being rotatable on said frame and being arcuate and having a peripheral arcuate semi-bore die face cooperating with said straight die face to engage tubing therebetween, an element connected to and movable with said other die member, means arranged to clamp tubing to said other one of said die members, tirst'hydraulic means for rotating said other one of said die members relative to the slidably mounted die member, second hydraulic means arranged to automatically actuate the clamping means prior to actuation of said rotating means, a fluid pressure source arranged to deliver uid to said first and second hydraulic means to operate the same, conduit'means connecting said fluid pressure source to said first and second hydraulic means, a pressure responsivevalve in the conduit between said tluid pressure Vsource and said first hydraulic means arranged to assure operation of said second hydraulic means prior to operation of said first hydraulic means, valve means controlling the operativeness of said first hydraulic means, said valve means being spaced a predetermined distance from said element in the path of movement of said element and being actuated by said element upon rotation of said rotatable die member to a predetermined position for disabling said iirst hydraulic means, and means automatically operated after disabling of said first hydraulic means for altering the effective spacing between said valve means and said element to control the degree ot successive rotational movements of said rotatable die member.

2. ln a bending machine of the character described, a rotatable die member, irst means arranged to rotate said die member, control means for said rotating means effective to disable the same, said rotating means having an element movable into engagement with said control means for actuating said control means, a plurality of shim members each selectively movable in predetermined order between said control means and said control element, means mounting said shim members for movement between said control means and said control element, and means automatically operated upon successive operation of said rotating means to move successive ones of said shim members between said control means and said element to thereby eiiectively change the distance between said control means and said control element to control the degree of successive rotational movements of. said rotatable die member.

3. In a bending machine of the character described, a movable die member, means arranged to move said die member, control means for said moving means elective to disable the same, said control means being positioned in the path of movement of an element of said moving means for actuating said control means, a shim turret having a plurality of shim members each selectively and adjustably positioned, and means operated by said first means for automatically rotating said shim turret to selectively dispose one of said shim members between said element and said control means, means mounting said shim turret for movement along the central axis of said turret to thereby effectively alter the distance between said control means and said element to control the degree of successive movements of said movable die.

4. In a bending machine of the character described, a rotatable die member, a cooperating slidable die member, first hydraulically operated clamping means on one of said die members arranged to clamp tubing thereon, second hydraulically operated means arranged to move one of said die members, conduit means, a source of iiuid pressure connected through said conduit means to said first and second means, pressure responsive valve means in said conduit means arranged to prevent operation of said second means until said iirst means is operated to thereby assure operation of said first means before operation of said second means, a control valve for said hydraulic moving means operative to disable said moving means, said moving means having an element actuated thereby arranged to operate said control valve, a plurality of positionable shim means interposed between said control valve and said element, means mounting said shim means for movement in the direction of the effective thickness of said shim means, means operated by said second means for automatically and selectively interposing, in predetermined order, said shim means between said control valve and said element to effectively vary the spacing between said control valve and said element to thereby control the degree of movement of said moving means.

5. In a bending machine of the character described, a frame, a die member rotatably mounted on said frame and having an arcuate die face with an arcuate peripheral semi-bore therein to engage tubing, an element connected to and movable with said die member, iirst hydraulically operated means mounted on said die member arranged to clamp tubing thereon, second hydraulically operated means for rotating said die member, a second die member slidably mounted on said frame and having a straight die face thereon with a semi-bore therein cooperating with the semi-bore of the irst mentioned die member to engage tubing therebetween, a fluid pressure source arranged to deliver fluid under pressure to said first and to said second means to operate the same, conduit means extending from said iiuid pressure source to said first and second means, and a pressure responsive valve in at least one of said conduits controlled by the pressure therein and arranged to automatically prevent the delivery of uid under operating pressure to said second means until the pressure of fluid delivered to said iirst means is stabilized to thereby assure operation of said clamping means before operation of said rotating means, valve means controlling the operativeness of said second means, said valve means being spaced a predetermined distance from said element in the path of movement of said element and being actuated by said element upon rotation of said second die to a predetermined position for disabling said rotating means, and means automatically operated after disabling of said rotating means for altering the effective spacing between said valve means and said element to control the degree of successive rotational movements of said second die.

6. In a bending machine of the character described, a frame, a first die slidably mounted on said frame, said first die having a straight die face with a straight semibore therein, a second arcuate die member with a semibore in its peripheral face cooperatinor with the straight semi-bore on the first die to engage tubing therebetween, an element connected to and movable with, said arcuate die member, said second die having mounted thereon a tube gripping clamp to maintain tubing aligned with the semi-bore in said arcuate die member, first hydraulic means actuating said gripping clamp, second hydraulic means for rotating said second die, and means controlled by pressure of fluid applied to said first hydraulic means for automatically assuring the operation of said first hydraulic means prior to operation of said second hydraulic means, valve means controlling the operativeness of said second means, said valve means being spaced a predetermined distance from said element in the path of movement of said element and being actuated by said element upon rotation of said second die to a predetermined position for disabling said rotating means, and means automatically operated after disabling of said rotating means for altering the effective spacing between said valve means and said element to control the degree of 'successive rotational movements of said second die.

7. In a bending machine of the character described, a longitudinally extending frame, a piston cylinder assembly mounted on said frame for movement of said piston generally along the longitudinal axis of said frame, a rack member connected to the piston of said assembly and moved thereby, a shaft extending transversely of said frame, a gear mounted on said shaft and cooperating with said rack, a pair of arcuate die members with a semi-bore on each of their peripheral faces mounted respectively on opposite ends of said shaft, tube clamping means mounted on each of said arcuate die members and adapted to clamp tubing in fixed position with respect thereto, a second pair of die members slidably mounted on said frame and having a straight plane face with a straight semi-bore therein each cooperating with a corresponding one of said arcuate semi-bores of the respective arcuate dies so as to engage tubing therebetween, hydraulic means actuating each of said tube clamping means1 said piston cylinder assembly being eiective to rotate said arcuate dies, valve means mounted on said frame in spaced relationship to said rack for actuation thereby, said valve means controlling the effectiveness of said piston cylinder. assembly to move said arcuate dies, a rotatable turret with different shims of different thickness mounted thereon for selective interpositioning between said rack and said valve means, and means operated automatically with movement of said rack to progressively move said turret to thereby interposition a diierent shim between said rack and said valve means.

References Cited in the file of this patent UNITED STATES PATENTS 1,244,664 Warren Oct. 30, 1917 1,261,229 Hansen Apr. 2, 1918 1,775,761 Harvey Sept. 16, 1930 1,826,403 OBrien Oct. 6, 1931 1,848,753 Spate Mar. 8, 1932 1,933,320 Eaton Oct. 31, 1933 10 Lyons Aug. 30, 1938 Cotner May 13, 1941 Moss Feb. 17, 1942 Pearne Apr. 14, 1942 Brooks June 16, 1942 Parker Dec. 22, 1942 Parker Dec. 22, 1942 Robinson Jan. 5, 1943 Bucklein Oct. 19, 1943 Duer Sept. 12, 1944 Hull Aug. 2, 1949 FOREIGN PATENTS France Dec. 14, 1904 

